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Open Access 01-12-2022 | Research article

Nudging customers towards healthier food and beverage purchases in a real-life online supermarket: a multi-arm randomized controlled trial

Authors: Josine M. Stuber, Jeroen Lakerveld, Loes W. Kievitsbosch, Joreintje D. Mackenbach, Joline W. J. Beulens

Published in: BMC Medicine | Issue 1/2022

Abstract

Background

Nudging is increasingly used to promote healthy food choices in supermarkets. Ordering groceries online is gaining in popularity and nudging seems efficacious there as well, but is never comprehensively tested in real-life. We evaluated the real-life effectiveness of nudging in an online supermarket on healthy food purchases.

Methods

We conducted a multi-arm, parallel-group, individually randomized controlled trial in an online supermarket. During 1 month, all customers were randomized to (1) control condition, (2) information nudges, (3) position nudges, and (4) information and position nudges combined. Allocation was concealed and customers were not blinded, but unaware of the intervention. Mean differences between the control condition and the intervention arms in the total percentage of healthy purchases were assessed with a linear mixed model. We tested for effect modification by area-level deprivation.

Results

Based on sales data from 11,775 shoppers, no overall significant effects were detected. Yet, effects were modified by area-level deprivation (p_{Arm 2} < 0.001). Among shoppers from deprived areas, those allocated to information nudges purchased a 2.4% (95%CI 0.8, 4.0) higher percentage of healthy products compared to controls. No significant differences were observed for position (− 1.3%; 95%CI − 2.8, 0.3) and combined nudges (− 0.1%; 95%CI − 1.7, 1.5). Shoppers from non-deprived areas exposed to information nudges (− 1.6%; 95%CI − 3.2, − 0.1) and the combined nudges (− 2.1%; 95%CI − 3.6, − 0.6), but not position nudges (− 0.9%; 95%CI − 2.4, 0.7), purchased a lower percentage of healthy products.

Conclusion

Information nudges in an online supermarket can increase healthy product purchases, but only for those living in deprived areas. The adverse effects found on purchasing behaviors for those from non-deprived areas call for further research. Further research should also focus on real-life effects of online healthy food nudging as part of a broader nutrition intervention strategy, and on the equitability of the online nudging intervention within populations.

Trial registration

Retrospectively registered in the ISRCTN registry at May 21, 2021 (ISRCTN10491616).

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Collaborators GBDRF. Global, regional, and national comparative risk assessment of 84 behavioural, environmental and occupational, and metabolic risks or clusters of risks for 195 countries and territories, 1990–2017: a systematic analysis for the Global Burden of Disease Study 2017. Lancet. 2018;392(10159):1923–94.CrossRef

Petrovic D, de Mestral C, Bochud M, Bartley M, Kivimäki M, Vineis P, et al. The contribution of health behaviors to socioeconomic inequalities in health: a systematic review. Prev Med. 2018;113:15–31. https://doi.org/10.1016/j.ypmed.2018.05.003.CrossRefPubMed

Kahneman D. Thinking, Fast and Slow. Fortune. 2015;172(1):20.

Adams J, Mytton O, White M, Monsivais P. Why are some population interventions for diet and obesity more equitable and effective than others? The role of individual agency. Plos Med. 2016;13(4):e1001990.CrossRef

Harbers MC, Beulens JWJ, Rutters F, de Boer F, Gillebaart M, Sluijs I, et al. The effects of nudges on purchases, food choice, and energy intake or content of purchases in real-life food purchasing environments: a systematic review and evidence synthesis. Nutr J. 2020;19(1):103. https://doi.org/10.1186/s12937-020-00623-y.CrossRefPubMedPubMedCentral

Hollands GJ, Bignardi G, Johnston M, et al. The TIPPME intervention typology for changing environments to change behaviour. Nat Hum Behav. 2017;1(8):1–9.

Egnell M, Boutron I, Peneau S, et al. Randomised controlled trial in an experimental online supermarket testing the effects of front-of-pack nutrition labelling on food purchasing intentions in a low-income population. Bmj Open. 2021;11(2):e041196. https://doi.org/10.1136/bmjopen-2020-041196.CrossRefPubMedPubMedCentral

Finkelstein EA, Ang FJL, Doble B. Randomized trial evaluating the effectiveness of within versus across-category front-of-package lower-calorie labelling on food demand. Bmc Public Health. 2020;20(1):312.CrossRef

Finkelstein EA, Doble B, Ang FJL, Wong WHM, van Dam RM. A randomized controlled trial testing the effects of a positive front-of-pack label with or without a physical activity equivalent label on food purchases. Appetite. 2021;158:104997. https://doi.org/10.1016/j.appet.2020.104997.CrossRefPubMed

10.

Shin S, van Dam RM, Finkelstein EA. The Effect of Dynamic Food Labels with Real-Time Feedback on Diet Quality: Results from a Randomized Controlled Trial. Nutrients. 2020;12(7):2158.CrossRef

11.

Vanderlee L, Franco-Arellano B, Ahmed M, Oh A, Lou W, L'Abbe MR. The efficacy of 'high in' warning labels, health star and traffic light front-of-package labelling: an online randomised control trial. Public Health Nutr. 2021;24(1):62–74. https://doi.org/10.1017/S1368980020003213.CrossRefPubMed

12.

Fialon M, Egnell M, Talati Z, et al. Effectiveness of different front-of-pack nutrition labels among Italian consumers: results from an online randomized controlled trial. Nutrients. 2020;12(8):2307.CrossRef

13.

Finkelstein EA, Ang FJL, Doble B, Wong WHM, van Dam RM. A randomized controlled trial evaluating the relative effectiveness of the multiple traffic light and nutri-score front of package nutrition labels. Nutrients. 2019;11(9):s.CrossRef

14.

Arslain K, Gustafson CR, Rose DJ. Point-of-decision prompts increase dietary fiber content of consumers’ food choices in an online grocery shopping simulation. Nutrients. 2020;12(11):3487.CrossRef

15.

Franco-Arellano B, Vanderlee L, Ahmed M, Oh A, L'Abbe M. Influence of front-of-pack labelling and regulated nutrition claims on consumers' perceptions of product healthfulness and purchase intentions: A randomized controlled trial. Appetite. 2020;149:104629. https://doi.org/10.1016/j.appet.2020.104629.CrossRefPubMed

16.

Ducrot P, Julia C, Mejean C, et al. Impact of different front-of-pack nutrition labels on consumer purchasing intentions a randomized controlled trial. Am J Prev Med. 2016;50(5):627–36. https://doi.org/10.1016/j.amepre.2015.10.020.CrossRefPubMed

17.

Koutoukidis DA, Jebb SA, Ordonez-Mena JM, et al. Prominent positioning and food swaps are effective interventions to reduce the saturated fat content of the shopping basket in an experimental online supermarket: a randomized controlled trial. Int J Behav Nutr Phy. 2019;16(1):50. https://doi.org/10.1186/s12966-019-0810-9.CrossRef

18.

Payne Riches S, Aveyard P, Piernas C, Rayner M, Jebb SA. Optimising swaps to reduce the salt content of food purchases in a virtual online supermarket: a randomised controlled trial. Appetite. 2019;133:378–86. https://doi.org/10.1016/j.appet.2018.11.028.CrossRefPubMedPubMedCentral

19.

Breugelmans E, Campo K. Effectiveness of instore displays in a virtual store environment. J Retail. 2011;87(1):75–89. https://doi.org/10.1016/j.jretai.2010.09.003.CrossRef

20.

Breugelmans E, Campo K, Gijsbrechts E. Shelf sequence and proximity effects on online grocery choices. Market Lett. 2007;18(1-2):117–33. https://doi.org/10.1007/s11002-006-9002-x.CrossRef

21.

Coffino JA, Udo T, Hormes JM. Nudging while online grocery shopping: A randomized feasibility trial to enhance nutrition in individuals with food insecurity. Appetite. 2020;104714:104714. https://doi.org/10.1016/j.appet.2020.104714.CrossRef

22.

Marty L, Cook B, Piernas C, Jebb SA, Robinson E. Effects of labelling and increasing the proportion of lower-energy density products on online food shopping: a randomised control trial in high- and low-socioeconomic position participants. Nutrients. 2020;12(12):3618.CrossRef

23.

Forwood SE, Ahem AL, Marteau TM, Jebb SA. Offering within-category food swaps to reduce energy density of food purchases: a study using an experimental online supermarket. Int J Behav Nutr Phy. 2015;12(1):85. https://doi.org/10.1186/s12966-015-0241-1.CrossRef

24.

Dubois P, Albuquerque P, Allais O, Bonnet C, Bertail P, Combris P, et al. Effects of front-of-pack labels on the nutritional quality of supermarket food purchases: evidence from a large-scale randomized controlled trial. J Acad Market Sci. 2021;49(1):119–38. https://doi.org/10.1007/s11747-020-00723-5.CrossRef

25.

Sacks G, Tikellis K, Millar L, Swinburn B. Impact of 'traffic-light' nutrition information on online food purchases in Australia. Aust Nz J Publ Heal. 2011;35(2):122–6. https://doi.org/10.1111/j.1753-6405.2011.00684.x.CrossRef

26.

Lakerveld J, Mackenbach JD, de Boer F, Brandhorst B, Broerse JEW, de Bruijn GJ, et al. Improving cardiometabolic health through nudging dietary behaviours and physical activity in low SES adults: design of the Supreme Nudge project. Bmc Public Health. 2018;18(1):899. https://doi.org/10.1186/s12889-018-5839-1.CrossRefPubMedPubMedCentral

27.

Juszczak E, Altman DG, Hopewell S, Schulz K. Reporting of Multi-Arm Parallel-Group Randomized Trials: Extension of the CONSORT 2010 Statement. JAMA. 2019;321(16):1610–20. https://doi.org/10.1001/jama.2019.3087.CrossRefPubMed

28.

SCP. The Netherlands Institute for Social Research. Status scores 2018. Den Haag Neth Inst Soc Res. 2018.

29.

Stuber JM, Mackenbach JD, de Boer FE, de Bruijn GJ, Gillebaart M, Harbers MC, et al. Reducing cardiometabolic risk in adults with a low socioeconomic position: protocol of the Supreme Nudge parallel cluster-randomised controlled supermarket trial. Nutr J. 2020;19(1):46. https://doi.org/10.1186/s12937-020-00562-8.CrossRefPubMedPubMedCentral

30.

Middel CNH, Schuitmaker-Warnaar TJ, Mackenbach JD, Broerse JEW. Designing a healthy food-store intervention; a co-creative process between interventionists and supermarket actors. Int J Health Policy Manag. 2021. https://doi.org/10.34172/ijhpm.2021.110.

31.

Harbers MC, Middel CNH, Stuber JM, Beulens JWJ, Rutters F, van der Schouw YT. Determinants of food choice and perceptions of supermarket-based nudging interventions among adults with low socioeconomic position: the SUPREME NUDGE Project. Int J Env Res Pub He. 2021;18(11):6175.CrossRef

32.

Kromhout D, Spaaij CJ, de Goede J, Weggemans RM. The 2015 Dutch food-based dietary guidelines. Eur J Clin Nutr. 2016;70(8):869–78. https://doi.org/10.1038/ejcn.2016.52.CrossRefPubMedPubMedCentral

33.

Brink E, van Rossum C, Postma-Smeets A, et al. Development of healthy and sustainable food-based dietary guidelines for the Netherlands. Public Health Nutr. 2019:1–17.

34.

Ren SQ, Lai H, Tong WJ, Aminzadeh M, Hou XZ, Lai SH. Nonparametric bootstrapping for hierarchical data. J Appl Stat. 2010;37(9):1487–98. https://doi.org/10.1080/02664760903046102.CrossRef

35.

Bender R, Lange S. Adjusting for multiple testing--when and how? J Clin Epidemiol. 2001;54(4):343–9. https://doi.org/10.1016/S0895-4356(00)00314-0.CrossRefPubMed

36.

Steindl C, Jonas E, Sittenthaler S, Traut-Mattausch E, Greenberg J. Understanding psychological reactance new developments and findings. Z Psychol. 2015;223(4):205–14. https://doi.org/10.1027/2151-2604/a000222.CrossRefPubMedPubMedCentral

37.

Manstead ASR. The psychology of social class: how socioeconomic status impacts thought, feelings, and behaviour. Brit J Soc Psychol. 2018;57(2):267–91. https://doi.org/10.1111/bjso.12251.CrossRef

38.

Franco-Arellano B, Vanderlee L, Ahmed M, Oh A, L'Abbe M. Influence of front-of-pack labelling and regulated nutrition claims on consumers' perceptions of product healthfulness and purchase intentions: a randomized controlled trial (vol 149, 104629, 2020). Appetite. 2020;155:104629.CrossRef

39.

Ducrot P, Chantal J, Mejean C, et al. Impact of different front-of-pack nutrition labels on consumer purchasing intentions: results of a randomized controlled trial. Ann Nutr Metab. 2015;67:489–90.

40.

de Wijk RA, Maaskant AJ, Polet IA, Holthuysen NTE, van Kleef E, Vingerhoeds MH. An in-store experiment on the effect of accessibility on sales of wholegrain and white bread in supermarkets. Plos One. 2016;11(3).

41.

Stuber JM, Hoenink JC, Beulens JWJ, Mackenbach JD, Lakerveld J. Shifting toward a healthier dietary pattern through nudging and pricing strategies: a secondary analysis of a randomized virtual supermarket experiment. Am J Clin Nutr. 2021;114(2):628–37. https://doi.org/10.1093/ajcn/nqab057.CrossRefPubMedPubMedCentral

42.

Jilcott Pitts SB, Ng SW, Blitstein JL, Gustafson A, Niculescu M. Online grocery shopping: promise and pitfalls for healthier food and beverage purchases. Public Health Nutr. 2018;21(18):3360–76. https://doi.org/10.1017/S1368980018002409.CrossRefPubMed

Title: Nudging customers towards healthier food and beverage purchases in a real-life online supermarket: a multi-arm randomized controlled trial
Authors: Josine M. Stuber
Jeroen Lakerveld
Loes W. Kievitsbosch
Joreintje D. Mackenbach
Joline W. J. Beulens
Publication date: 01-12-2022
Publisher: BioMed Central
Published in: BMC Medicine / Issue 1/2022
Electronic ISSN: 1741-7015
DOI: https://doi.org/10.1186/s12916-021-02205-z

Keynote webinar | Spotlight on sleep in brain health

Springer Medicine

Nudging customers towards healthier food and beverage purchases in a real-life online supermarket: a multi-arm randomized controlled trial

Abstract

Background

Methods

Results

Conclusion

Trial registration

Keynote webinar | Spotlight on sleep in brain health

Springer Medicine

Abstract

Background

Methods

Results

Conclusion

Trial registration

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